Transportation Conformity

Information about transportation conformity in Texas, including applicable state implementation plan (SIP) and rule revisions, and information for areas with transportation conformity requirements

Background

Transportation conformity is a requirement of the federal Clean Air Act (CAA) to ensure that air quality in nonattainment and maintenance areas for transportation-related National Ambient Air Quality Standards (ozone, particulate matter (PM), carbon monoxide (CO), and nitrogen dioxide (NO2)) is not negatively impacted by federal funding and approval of transportation activities. Nonattainment areas are those that do not currently meet an air quality standard, and maintenance areas are those that were previously nonattainment for an air quality standard. Transportation conformity applies to transportation plans, transportation improvement programs, and projects funded or approved by the Federal Highway Administration (FHWA) or the Federal Transit Administration (FTA).

Transportation conformity requires an affected area to conduct an analysis to estimate emissions for the pollutant(s) under which the area is nonattainment or maintenance that are expected to result from the area’s transportation system. The analysis must demonstrate that those estimated emissions do not exceed the emissions limit established in the state’s air quality SIP. The emissions limit is referred to as the motor vehicle emissions budget (MVEB).

Conformity determinations also ensure that transportation and air quality agencies are in consultation with one another, and that transportation control measures in an approved state air quality SIP are being timely implemented. Consultation partners include the affected metropolitan planning organization (MPO) and local transit and air quality offices, the Texas Department of Transportation, the Texas Commission on Environmental Quality, the United States Environmental Protection Agency (EPA), FTA, and FHWA.

Transportation Conformity Links

State SIP and Rule Revisions

The Texas transportation conformity rule describes the state's interagency consultation procedures and incorporates by reference the federal transportation conformity rule. Transportation conformity was incorporated into the state SIP in 1994 as required under the CAA Amendments of 1990, §176(c). Since 1994, the state SIP and transportation conformity rule have been revised to incorporate amendments to the federal transportation conformity rule. The most recent revision was adopted by the Commission on June 27, 2007, and the EPA finalized approval effective December 12, 2014.